Lake Ecology & Preservation

Scientific name: Myriophyllum spicatum L. Common name(s): Eurasian Water Milfoil
Eurasian water Milfoil is an "exotic" aquatic plant. Exotic means that it isn't native to the Adirondacks-- it is native to Europe, Asia and Northern Africa. Aquatic means that it lives in the water. Eurasian Water Milfoil was brought to North America in the 1940s. Eurasian Water Milfoil likes to live in lakes, ponds, shallow water reservoirs and slow moving rivers and streams. It reproduces very fast and in many different ways. If a stem breaks off, it can start a new plant. It also produces flowers and seeds that appear above the water, while the rest of the plant is under water, and it spreads by roots or runners (stolons) in the ground. It is also very tolerant of cold water, so it can grow fast in cold Adirondack lakes in early spring.

Eurasian Water Milfoil grows and spreads really fast. So fast, that it can choke out native plants and reduce the amount of light that reaches into the lake. This aggressive growth kills off other native aquatic plants. And when the native plants can't grow, other aquatic species that rely on the native plants for food and shelter have trouble surviving. Eurasian Water Milfoil's dense growth makes it difficult for invertebrates and other organisms that fish eat to survive.So, with less to eat and less open water, fish populations also decrease.

Have you ever tried to swim in weeds?
Kinda' hard, isn't it. Well, imagine a whole lake full of Eurasian Water Milfoil -- so full that it's almost impossible to swim in, fish in, or drive a boat through. If you were a fish it would be really hard to live in a lake so full of milfoil that you couldn't swim around and catch food.

What Does It Look Like?
Eurasian Milfoil looks almost like Northern Milfoil, which is native to Minnesota. But, Eurasian Milfoil has 12 to 21 leaflet pairs, while Northern Milfoil has only 5 to 10 leafelet pairs. But, the best way to tell the two apart is to pick them up. Eurasian Milfoil is limp and soft, while Northern Milfoil (the native species) is stiff and bristly.

To prevent introducing Eurasian Water Milfoil into lakes, be sure to do the following:

  • Remove all plant materials from your boat, anchor, trailer and anything that entered the water after you take the boat out of the water and before you leave the boat access area. Drain livewells and bilge water before you leave the boat access area.
  • Make sure your bait bucket doesn't have any plant material in or on it. Be sure to empty your bait bucket on land -- never dump live fish from a bait bucket into a body of water.
  • Wash down your boat, trailer and tackle with hot water when you get home to kill off any hitchikers that could be transported into other lakes.

For more information on Milfoil and other invasive plants please visit

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